Front-end shimmy comming down the mountain

Befor I retired, I worked for a company that had a large fleet of 3/4 ton and 1 ton pick-ups and vans. Working 2nd shift, I spent a lot of time BSing with the mechanic that maintained the fleet. Company policy required him to purchase OEM parts. That meant that he had to buy the OEM Chinese disc rotors. He turned ALL the replacement rotors befor installing them, because he swore that they came from China warped. He clamed that turning them doubled the life of the brakes, and cut his work load in half.

ol Bombero-JC wrote:

Cummins12V98 wrote:

Francesca Knowles wrote:

Water-Bug wrote:

EDIT Darn Chinese brake rotors. They are OEM on just about everything.

:h

Will brake rotors produced elsewhere yield a different result in the same circumstances? And if so, what Country of Origin/brand do you recommend?

Yes! US or Canadian made quality brands.

No!

Rotor brand choice is secondary to proper hill descending technique..:S

If you've been behind the/a wheel long enough - that "event" would/could (did) occur *before* off-shore parts became the norm.

.

Sorry but a quality rotor is less likely to do as the op has described. Those are usually US or Canadian made.

tsetsaf wrote:
Drilled and slotted look cool but actually hurt braking performance for heavy hauling. Op has the answers he needs: 1.check the computer 2 check the rotors 3 use the eb more and service brakes less.

Forgot to say to also check the controller setting. May simply need to be more aggressive with the trailer brakes.

Lyle

Water-Bug wrote:

RAS43 wrote:

Red-Rover wrote:
When my front wheel brake rotors overheat I get steering wheel shimmy and yes, the brake mechanics will check out okay after cooling.

My thoughts also. I have experienced the same symptoms in our mountains.

Simply said, your front brake rotors are warping under temperature. They may have been seriously over tempt at some point or suddenly cooled while hot. Driving into standing water with hot brakes will do it.

EDIT Darn Chinese brake rotors. They are OEM on just about everything.

That was also my first thought. Have had warped rotors a couple times in the past 40+ years. Also, bent drums, but that's way old-school. :-) Another thought... What about the ABS system malf'ing?

Lyle

Cummins12V98 wrote:

Francesca Knowles wrote:

Water-Bug wrote:

EDIT Darn Chinese brake rotors. They are OEM on just about everything.

:h

Will brake rotors produced elsewhere yield a different result in the same circumstances? And if so, what Country of Origin/brand do you recommend?

Yes! US or Canadian made quality brands.

No!

Rotor brand choice is secondary to proper hill descending technique..:S

If you've been behind the/a wheel long enough - that "event" would/could (did) occur *before* off-shore parts became the norm.

.

Sturgeon-Phish wrote:
Did you have the tow/haul engaged?

larry barnhart wrote:
Might be cause by improper torqueing of the lug nuts. Usually it shows up after tire work has been done

I found this to be true on our van after having new tires put on, it actually warped the rotor out of shape and we got the shimmy.

The impacts will have a preset value. What happens is they'll drive a lug nut down then go to the others. The first one driven down gets crazy tight. Re-torquing the lugnut may correct or at least make it better.
After tire work at a tire shop I now losen and retorque the lugnuts.

I also do as you and tell the man doing the torque to go to 120Lb and I will redo at home. I have had some way more torque than the 140 ft lbs our truck needs and almost could not loosen that lug nut.

chevman

rhagfo wrote:

larry barnhart wrote:
We don't have an EB brake and for what we tow it is not needed but I can see it would for a much bigger fifthwheel and I know I would like it. Starting slower down steep mountains is the key.
chevman

Really, you think that 35' Alpenlite is that lite? Maybe you feel you don't need one if you don't have one, but after installing mine, life is far better coming down a long steep grade.

The hills in the Oregon Coast range have some good grades in them, I can be traveling down at 60, drop to 4th (5 speed manual) and be down to 45 without touching the service brakes! If anywhere along that downgrade I need a panic stop, I still have COLD brakes both TV and 5er!!

I see an EB to be like 4X4 you don't need it UNTIL you need it!!!

Russ Larry's GM has grade braking unlike our Dodges that did not lock the TC in OEM trim! V8's seem to hold back better also. BIG difference!

I have the exhaust brake on a secondary switch to my smart controller and even with the TQ locked, the mighty Cummins just free wheels. Chris

larry barnhart wrote:
We don't have an EB brake and for what we tow it is not needed but I can see it would for a much bigger fifthwheel and I know I would like it. Starting slower down steep mountains is the key.
chevman

Really, you think that 35' Alpenlite is that lite? Maybe you feel you don't need one if you don't have one, but after installing mine, life is far better coming down a long steep grade.

The hills in the Oregon Coast range have some good grades in them, I can be traveling down at 60, drop to 4th (5 speed manual) and be down to 45 without touching the service brakes! If anywhere along that downgrade I need a panic stop, I still have COLD brakes both TV and 5er!!

I see an EB to be like 4X4 you don't need it UNTIL you need it!!!

Did you have the tow/haul engaged?

larry barnhart wrote:
Might be cause by improper torqueing of the lug nuts. Usually it shows up after tire work has been done

I found this to be true on our van after having new tires put on, it actually warped the rotor out of shape and we got the shimmy.

The impacts will have a preset value. What happens is they'll drive a lug nut down then go to the others. The first one driven down gets crazy tight. Re-torquing the lugnut may correct or at least make it better.
After tire work at a tire shop I now losen and retorque the lugnuts.

We don't have an EB brake and for what we tow it is not needed but I can see it would for a much bigger fifthwheel and I know I would like it. Starting slower down steep mountains is the key.
chevman